modelcontextprotocol / modelcontextprotocol/csharp-sdk

Support externally sourced JWT in Auth header from MCP client

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#917 2 comments 0 reactions 0 assignees View on GitHub

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area-auth enhancement P2 ready for work
Dominant language
C#
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Forks
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Avg merge
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Merged PRs (30d)
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Description

I have been using the MCP OAuth support and even DCR, which is awesome.
But there are other scenarios where we are building in using MCP Servers into some host that doesn't understand this protocol, or that doesn't have an OAuth 2.1 server available, but where we might have obtained a valid access token (Jwt Bearer token) through some other means.
In this case I would like to add this to the MCP client so that it can be passed in the Authorization: Bearer {jwt} header on each call.
Is there a good way to do this - and if not can there be a way that feel intuitive to provide that kid of 'out of band' auth support for the MCP calls?

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Research direction

No files, tests, or entry points are mentioned. Start by reviewing the MCP client’s existing OAuth support and how it constructs the Authorization header, then determine where an externally supplied JWT could be provided. Done means the client can send the supplied bearer token on each call without requiring an OAuth 2.1 server.

Written by the indexing model from the issue text.

Assessment

Tech stack
csharp
Domain
authentication
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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